feat(admin): 存储管理 - 新增资源只读查询、统计与预览

Adapted from ddcat-ai/open-ai-canvas#339

Original commit: fcdbe2aa833f31f683f709b7f409a0534ed78e20

Refs #339

Co-authored-by: 宇熙 <101980758+yuxiwl@users.noreply.github.com>

backend/internal/handler/admin_storage.go

@@ -0,0 +1,72 @@
+package handler
+
+import (
+	"strconv"
+
+	"infinite-canvas/backend/internal/service"
+
+	"github.com/gin-gonic/gin"
+)
+
+func RegisterAdminStorageRoutes(r *gin.RouterGroup, svc *service.Service) {
+	r.GET("/admin/storage/stats", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		stats, err := svc.AdminStorageStats(user)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, gin.H{"stats": stats})
+	})
+
+	r.GET("/admin/resources", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
+		limit, _ := strconv.Atoi(c.DefaultQuery("limit", "20"))
+		result, err := svc.AdminResourcePage(user, service.AdminResourceQuery{
+			Keyword: c.Query("keyword"), Kind: c.Query("kind"), Status: c.Query("status"),
+			Provider: c.Query("provider"), UserID: c.Query("userId"), Page: page, Limit: limit,
+		})
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		ok(c, result)
+	})
+
+	r.GET("/admin/resources/:id/file", func(c *gin.Context) {
+		user, err := currentUser(c, svc)
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		stream, err := svc.OpenResourceRangeAsAdmin(user, c.Param("id"), c.GetHeader("Range"))
+		if err != nil {
+			failService(c, err)
+			return
+		}
+		defer stream.Body.Close()
+		mimeType := stream.Resource.MimeType
+		if mimeType == "" {
+			mimeType = "application/octet-stream"
+		}
+		c.Header("Cache-Control", "private, no-cache")
+		c.Header("Accept-Ranges", stream.AcceptRanges)
+		c.Header("X-Content-Type-Options", "nosniff")
+		if stream.ContentRange != "" {
+			c.Header("Content-Range", stream.ContentRange)
+		}
+		if c.Query("download") == "1" {
+			c.Header("Content-Disposition", "attachment")
+		}
+		c.DataFromReader(stream.StatusCode, stream.ContentLength, mimeType, stream.Body, nil)
+	})
+}